Increased emphasis on weight savings has led to a wider use of plastic for wheel covers.
Prior art retainers are not well suited for the retention of wheel covers to cast wheels of the type having a series of circumferentially spaced radially extending reinforcement ribs. Such retainers include metal clips secured to the periphery of the wheel cover for engaging the peripheral flange of a conventional wheel such as shown in Beisch U.S. Pat. No. 4,229,047. Cast rib wheels lack such a peripheral flange. Meyers U.S. Pat. No. 4,012,078 and Main U.S. Pat. No. 4,004,837 show the use of resilient plastic fingers which snap fit within annular recesses in the wheel hub. Since cast rib wheels do not have a hub adaptable to the use of such fingers and since this type of retention requires the use of plastic materials with above average creep and thermal properties, this type of retainer is also not well suited for use with cast rib wheels. Dessinger, U.S. Pat. No. 3,883,881 shows integral plastic retainers which include a circumferentially extending peripheral flange which snaps into a matching flange on the wheel cover. Again this type of retainer is not well adaptable for use with cast ribbed wheels.